mysql57: follow SELECT_LEX::non_agg_fields API change
mysql57: follow SELECT_LEX::non_agg_fields API change

It's not the same condition. We may need to use a feature in
sql/aggregate_check.h.

yoku0825/mroonga,mroonga/mroonga,naoa/mroonga,mroonga/mroonga,naoa/mroonga,yoku0825/mroonga,naoa/mroonga,yoku0825/mroonga,yoku0825/mroonga,naoa/mroonga,naoa/mroonga,yoku0825/mroonga,mroonga/mroonga,naoa/mroonga,mroonga/mroonga,yoku0825/mroonga